C 3500 Truck 2WD V8-6.6L DSL Turbo VIN 1 (2002)
Automatic Transmission Dipstick - Dipstick Tube: Customer Interest
A/T - Fluid/Oil Leak from Transmission Vent
TECHNICAL
Bulletin No.: 10-07-30-001C
Date: April 13, 2011
Subject: Fluid/Oil Leak During Cold Weather from Transmission Vent (Early Models-Replace Transmission Fluid Level Indicator and Install New
Transmission Vent Assembly)
Models:
2001-2012 Chevrolet Silverado 2500HD-3500HD Series
2001-2012 GMC Sierra 2500HD-3500HD Series
Equipped with Allison(R) LCT 1000 Automatic Transmission (RPOs M74, MW7)
Supercede:
This bulletin is being revised to add the 2012 model year and update information. Please discard Corporate Bulletin Number 10-07-30-001B (Section 07
- Transmission/Transaxle).
Condition
Some customers may comment on a small red fluid/oil leak during cold weather. Upon further investigation, the technician may find a small fluid leak in
the area at the back of the transmission by the vent.
Cause
This condition may be caused by fluid being discharged out the transmission vent due to a low transmission fluid fill. During extreme cold weather,
(approximately -25°C (-15°F or colder), low fluid fill can cause the transmission pump to ingest air which can aerate the fluid and push some fluid out
the vent.
Correction
On 2001 through 2012 models, verify the transmission is full of fluid. Follow the SI fluid checking procedure to PROPERLY check the transmission
fluid level using the Hot Check Procedure.
Important
Ensure that the fluid level is at the top of the HOT band when the transmission fluid temperature is 79°C (175°F). Refer to SI Document ID#
2408059 for the proper fluid level checking procedure.
Note
Only on 2001-2004 models, replace the transmission fluid indicator (dipstick) with a new vented indicator, P/N 15794381.
